This is a pipe dream and it will never go through. Implementing these kind of measures will have consequences, both on freedom/liberty and the internet economy.
Plus, who decides which websites are suitable, and which are not? This system is just begging to be exploited by politicians and corporate lobbyists for their personal gain.
If parents want to "protect" their children from "harmful" websites, then they should do it themselves. There is software available for that purpose.
At most, ISPs could include this type of "child protection" software in the CDs they usually send to clients when they purchase an internet connection. People could then choose if they want to have it on their computer or not. That would be acceptable.
But I think we all know this douchebag only wants to score political brownie points with some voters, being mostly paranoid insecure parents and other people that are scared of their own shadow.